1. Field of the Invention
The invention relates to a projection television apparatus having three monochromatic picture tubes disposed in a planar orientation defining a central picture tube and two outer picture tubes. Each picture tube is provided with main vertical and horizontal deflection coils and auxiliary vertical and horizontal raster correction deflection coils.
2. Description of Related Art
In projection television apparatus, correction signals which compensate for defects in the raster coincidence, the picture tube geometry, the keystone distortion, the convergence and other defects, have to be supplied to each of the three picture tubes, in addition to the usual deflection signals for the horizontal deflection and the vertical deflection. Correction signals of this type are generally supplied to additional or auxiliary deflection coils which are arranged adjacent to the main deflection coils for the deflection in the horizontal deflection or the vertical direction and which have an appreciably reduced inductance relative to the main deflection coils.
New kinds of picture tubes have a curved phosphor screen. Such kinds of tubes make it possible to have a smaller separation between the picture tubes and the projection screen and thus a smaller depth of housing for the projection television receiver. On the other hand, such kinds of picture tubes require a greater amount of correction of the picture geometry.